<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>02_加减乘除</title>
</head>
<body>
<input type="text" placeholder="请输入数字1" id="#1" ><br>
<input type="text" placeholder="请输入数字2" id="#2" ><br>
<button onclick="calc('+')">加</button>
<button onclick="calc('-')">减</button>
<button onclick="calc('*')">乘</button>
<button onclick="calc('/')">除</button>
<h4>运算结果:<span></span></h4>
<script>
    function  calc(){
        let n1 = document.querySelector('#1').value;
        let n2 = document.querySelector('#2').value;
        n1 = parseFloat(n1);
        n2 = parseFloat(n2);

        let spanE = document.querySelector('span');

    }
</script>
</body>
</html>